Sienna Miller will star in the new 'G.I. Joe' movie.The British actress has signed up to play a "sexy raven-haired femme fatale baroness skilled in espionage" in the movie based on the original comic book series from the 40s about a military action hero.The film focuses on a Brussels-based task force of operatives known as G.I.J.O.E. - the Global Integrated Joint Operating Entity - who battle the evil Cobra organisation, headed by a Scottish arms dealer.Sienna, 25, is the first star to put her name to Paramount Pictures' big-budget project and casting is still ongoing for the other lead roles.Stephen Sommers, who directed 'The Mummy', will helm the film which is set to start shooting in mid-February next year.The movie is scheduled for release in August 2009.The name G.I. Joe was created by David Breger in 1942 when he was asked to produce a comic strip for US military magazines during World War II.The first series of G.I. Joe figures were produced by Hasbro toy company in 1964.